In a bowl, combine 6 tbsp lukewarm milk, 2 tsp yeast, and 2/3 cup flour. Cover and let it rest for 2-3 hours or overnight.

To the poolish, add 1 cup milk, 3 cups flour, 3.5 tbsp sugar, 2.5 tsp salt, 0.5 tbsp vanilla extract, and 0.5 tbsp softened butter. Mix for 3 minutes, let rest for 20 minutes, then mix for another 3-4 minutes until smooth. Allow the dough to rise for 1-2 hours until it doubles in size.

Flatten the dough slightly and refrigerate. In a separate bowl, beat 22 tbsp of butter until pliable. Shape it into a rectangle and chill it as well.

Roll the chilled dough into a large rectangle (about twice the size of your butter block). Place the butter block in the center, fold the dough over, and roll it out again. Refrigerate for 30 minutes after each fold.

In a small bowl, mix 1/2 cup granulated sugar, 1/4 cup brown sugar, 1 tbsp fresh orange zest, 1.5 tsp ground cinnamon, and 1/4 tsp salt.

Roll out the laminated dough one last time into a large rectangle. Brush it with 3 tbsp melted butter, sprinkle evenly with your filling mixture, and roll tightly into a log. Cut into 12 pieces and refrigerate for 30 minutes.

Let the buns rise at room temperature for 1 hour. Preheat the oven to 375°F and bake for 45-60 minutes or until golden brown and fragrant.